Multiple sql query or Cursor? - sql

Question

I need help on something that seems to be complex to me.
I made a query to create a tbl1 which is the Cartesian product of the tables Item and Warehouse. It give’s me back all items in all warehouses:
SELECT i.ItemID, w.WarehouseID
FROM Item i, Warehouse w
I made a second query (tbl2) where I check the date of the last document previous or equal to a variable date (#datevar) and whose quantity rule is 1 (PhysicalQtyRule = 1), this by Item and Warehouse, obtained from StockHistory table
SELECT MAX(CreateDate) AS [DATE1], ItemID, Quantity, WarehouseID
FROM StockHistory
WHERE PhysicalQtyRule = 1 AND CreateDate <= #datevar
GROUP BY ItemID, Quantity, WarehouseID
Now, I need more three steps:
Build a third table containing per item and warehouse the sum of quantity, but the quantity rule is 2 (PhysicalQtyRule = 2) and date between tbl2.date (if exists) and the date of the variable #datevar, obtained from the table StockHistory. Something like that:
SELECT ItemID, WarehouseID, SUM(Quantity)
FROM StockHistory
WHERE PhysicalQtyRule = 2 AND CreateDate > tbl2.DATE1 --If exists
AND CreateDate <= #datevar
GROUP BY ItemID, WarehouseID
Build a fourth table containing per item and warehouse the sum of quantity, but the quantity rule is 3 (PhysicalQtyRule = 3) and date between tbl2.date (if any) and the date of the variable #datevar, obtained from the table StockHistory. Something like that:
SELECT ItemID, WarehouseID, SUM(Quantity)
FROM StockHistory
WHERE PhysicalQtyRule = 3 AND CreateDate > tbl2.DATE1 --If exists
AND CreateDate <= #datevar
GROUP BY ItemID, WarehouseID
Create a final table based on the first one, with an sum quantity column, something like that:
SELECT i.ItemID, w.WarehouseID, tbl2.Quantity + tbl3.Quantity – tbl4.Quantity AS [Qty]
FROM Item i, Warehouse w
I don't know if need cursors (something new for me) or multiple querys, but it's important the best performance because my StockHistory table have millions of records.
Can anyone help-me please? Thank you!
Some sample data, only for one Item and one warehouse:
+--------+-------------+------------+-----------------+----------+
| ItemID | WarehouseID | CreateDate | PhysicalQtyRule | Quantity | Balance | comments
+--------+-------------+------------+-----------------+----------+
| 1234 | 11 | 2013-03-25 | 2 | 35 | 35 | Rule 2 = In
| 1234 | 11 | 2013-03-28 | 3 | 30 | 5 | Rule 3 = Out
| 1234 | 11 | 2013-04-01 | 1 | 3 | 3 | Rule 1 = Reset
| 1234 | 11 | 2013-07-12 | 2 | 40 | 43 | Rule 2 = In
| 1234 | 11 | 2013-09-05 | 3 | 20 | 23 | Rule 3 = Out
| 1234 | 11 | 2013-12-31 | 1 | 25 | 25 | Rule 1 = Reset
| 1234 | 11 | 2014-01-09 | 3 | 11 | 14 | Rule 3 = Out
| 1234 | 11 | 2014-01-16 | 3 | 6 | 8 | Rule 3 = Out
I want to know the balance on any variable date.

Answer 1

Without your data, I can't test this but I believe this should be your solution.
SELECT i.ItemID
,w.WarehouseID
,[Qty] = tbl2.Quantity + tbl3.Quantity – tbl4.Quantity
FROM Item i
CROSS JOIN Warehouse w
OUTER APPLY (
SELECT [DATE1] = MAX(sh.CreateDate)
,sh.ItemID
,sh.Quantity
,sh.WarehouseID
FROM StockHistory sh
WHERE sh.PhysicalQtyRule = 1 AND sh.CreateDate <= #datevar
AND i.ItemID = sh.ItemID
AND w.WarehouseID = sh.WarehouseID
GROUP BY sh.ItemID, sh.Quantity, sh.WarehouseID ) tbl2
OUTER APPLY (
SELECT sh.ItemID
,sh.WarehouseID
,[Quantity] = SUM(sh.Quantity)
FROM StockHistory sh
WHERE sh.PhysicalQtyRule = 2 AND sh.CreateDate > tbl2.DATE1 --If exists
AND sh.CreateDate <= #datevar AND i.ItemID = sh.ItemID
AND w.WarehouseID = sh.WarehouseID
GROUP BY sh.ItemID, sh.WarehouseID ) tbl3
OUTER APPLY (
SELECT sh.ItemID
,sh.WarehouseID
,[Quantity] = SUM(sh.Quantity)
FROM StockHistory sh
WHERE sh.PhysicalQtyRule = 3 AND sh.CreateDate > tbl2.DATE1 --If exists
AND sh.CreateDate <= #datevar AND i.ItemID = sh.ItemID
AND w.WarehouseID = sh.WarehouseID
GROUP BY sh.ItemID, sh.WarehouseID ) tbl4